Sparklehorn Kill Dry?

[felipesareas]

Hey Guys, I saw a post suggesting to lower R18 to 8.2K or 6.8K in the Sparklehorn  in order to achieve more wet signal at the mix knob. Is there any way to install a kill dry switch?  Maybe bypassing R18 would do so?

[mauman]

I'm looking at the schematic dated 6/2012.  On that one, to kill the dry, open up the path between R6 and pin 5 of IC1.  But pin 5 is also the bias for this half of the op amp (VB via R2) so you'll need to maintain the bias if you open that path. 

You could remove resistor R6 and use both holes in the PCB to wire a SPDT switch.  Lug 2 of the switch (swing contact) goes to the bottom hole of R6 on the PCB, which should connect to pin 5 of IC1 (as well as C5).  Lug 1 of the switch goes thru a new 1meg resistor to VB, this is "no-dry-but-maintain-bias."  You can pick up VB where R21/R22/R2 come together.  Lug 3 of the switch goes through a 1k resistor (R6) to the top hole of R6 on the PCB, which should connect to R5, this is "normal."  You might hear a pop if you flip the switch while the pedal is active.   

[felipesareas]

Thanks a lot for the Info, Mauman. I forgot to mention in my original post that my version is from 2014. I believe that in my schematic from 2014 that your R5  is my R2. Maybe your R6 (1k) was replaced with 2k so it's my R3?
Kind regards

[midwayfair]

This is a good schematic reading exercise, and an even better breadboarding exercise.

Load up the picture of the schematic in paint (or whatever) and outline the dry path in one color, and the delay path in another color.
Your intuition tells you you can do what you want with a switch. What can you do to make there be no dry signal path from the input to the output at all? What about no delay path?

Work out what the mix pot is doing. In which position would you get the most dry signal? In which would you get the least?

Pretend the mix pot wasn't a potentiometer. What would you do to make as much dry signal as possible? What about as little dry signal as possible?

[mauman]

^^+1!